Investigate the use of recycled polyvinyl chloride (PVC) particles in improving the mechanical properties of stone mastic asphalt (SMA)

Every year, millions of tons of industrial waste and household waste, including plastic waste, cause damage to the environment through landfilling, incineration, or dumping in open water. Polyvinyl chloride (PVC) is one of the most broadly used plastic materials in the modern world today, which can be reused in various industries by recycling waste. This matter can significantly help to improve environmental health. In this study, the impact of two kinds of recycled PVC (recycled water pipes and recycled candy wrappers) with three various percentages (2%, 3.5%, and 5% by weight of bitumen) on improving the mechanical properties of stone mastic asphalt (SMA) mixture has been investigated. For this purpose, in the present research, the Static creep test, Deformation strength test (Kim Test), Skid resistance test, indirect tensile strength (ITS) test, Semi-circular bending (SCB) fracture test, and conventional bitumen tests have been used. The conventional bitumen tests indicated that recycled PVC materials increased the softening point, viscosity, and specific gravity and reduced the penetration and the ductility of bitumen. Also, the results of mechanical tests illustrated that the addition of recycled water pipe particles and recycled candy wrapper particles improved the indirect tensile strength and increased the moisture resistance in stone mastic asphalt. However, increasing the percentage of these recycled materials to the asphalt mix had a negative effect on skid resistance. Regarding these recycled material's effects on rutting resistance, the Kim test depicted that raising the percentage of these recycled additives increases the rutting resistance of asphalt mixtures at high temperatures. Also, the static creep test revealed that the addition of these recycled PVCs reduces the accumulated permanent axial strain and increases the creep stiffness of stone mastic asphalt mixture. Moreover, based on the results of the fracture test, the addition of recycled PVC particles to the stone mastic asphalt mixture has a positive effect on the fracture energy at intermediate temperatures and intensity factor (K-eff) at sub-zero temperature. Finally, in a general conclusion, it can be stated that recycled water pipe additive has a more notable influence on the mechanical properties of SMA mixture than recycled candy wrapper additive.

Automated summary

Millions of tons of industrial and household waste, especially plastic waste, are causing damage to the environment through landfilling, incineration, and dumping. This study investigated the impact of different percentages of recycled PVC on the mechanical properties of stone mastic asphalt (SMA) mixture. The results showed that the addition of recycled PVC materials improved the moisture resistance and rutting resistance of SMA, but had a negative effect on skid resistance.